Vitamins

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Vitamins
Vitamins

Definition: vital dietary substances

Not CHO, Protein, or Fat
Necessary in very small quantities
to do special metabolic jobs
 Help regulate body processes


Especially B vitamins
Vitamins
Cannot be made by body in
sufficient amounts
Exception: Vitamin D
 Supplied by food
 Most work by combining with
protein to form co-enzymes
 Natural vs. Synthetic


Rates of absorption different
Vitamins

Provitamins


Antivitamins


antagonists
Avitaminosis


precursors to active vitamin
deficiency
Hypervitaminosis

too much
Vitamins
Grouped by solubility.
 Fat soluble I



A D E
K
H20 soluble
B complex
C
 B12
folate
 pantothenic acid
 biotin

Fat Soluble
Absorbed in lymphatic system
 Deficiencies occur with fat
malabsorption
 Attached to protein carriers
 Not excreted, stored if not needed
 Can be toxic

Water Soluble Vitamins
Absorbed directly through
intestinal wall
 Filtered by kidneys and excreted
if excess
 Tissues able to hold limited amounts
 May be able to become toxic
 Function as coenzymes for
production of energy

Vitamins

Megadose

more than 10 X RDA
Up to 35% of Americans take
vitamin supplements
 Food best source
 Supplements needed when diet
inadequate or during times of stress

Vitamin A

Generic term for several compounds
retinal
 retinol
 retinaldehyde
 retinoic acid

Vitamin A

Preformed vitamin A = retinol
found only in animal sources or
fortified foods
 6-12 months supply in body
 stores deplete in infectious disease
 major transport and storage form

• retinol binding protein picks up retinol from
liver, carries it in blood
Vitamin A
Provitamin A
 Beta carotene
 Plant source
 Supplies 2/3 Vitamin A necessary
 Converted retinal
retinol
 Extremely effective antioxidant

Vitamin A




Maintains cornea
Helps with light
detection at retina
Maintains integrity
of epithelial cells
Fights infection



Supports normal
bone and body
growth
Reproduction
Cell development
Vitamin A Deficiencies
Epithelial cells flatten and harden
from production of keratin
 Drying & hardening of cornea



xerosis
Xerophthalmianight blindness
 hardening of cornea
 complete blindness

Vitamin A Deficiencies

Mucous linings harden

increased tendency for infection
Skin
 Dry, rough, scaly “toad’s skin”
 Follicular hyperkeratosis
 Delayed sexual maturation/sterility

Vitamin A Toxicity

Acne medication


can cause birth defects
Overdosing
can cause birth defects
 joint pains
 loss of hair
 jaundice
 death

Vitamin A Sources




Liver
Fish Liver Oils
Whole and
Fortified milk and
dairy products
Dark green and
yellow-orange
vegetables
Vitamin D

Made in body with help of
ultraviolet rays


prohormone = calcitriol
Works in harmony with parathyroid
hormone
withdraws Ca++ from bone to maintain
Ca++
 calcitonin decreases bone withdrawal

Vitamin D
Liver manufactures precursor
 Migrates to skin-converted to #2
precursor with ultraviolet rays
 Liver and kidney convert #2
to active vitamin
 Absorption in small intestine
 Requires presence of bile salts

Vitamin D
Associated with Ca++ and Po4-3
metabolism
 Promotes normal bone
mineralization
 Basic cell processes in brain &
kidney, liver, skin, reproduction
 Immune system

Vitamin D Deficiencies
Bones fail to calcify
 Rickets or osteomalacia
can develop
 Muscle spasms and pain
 Repeated pregnancies and periods of
lactation
 Little sun exposure

Vitamin D Toxicity
Stored in adipose tissue
 Released slowly
 Bone pain & weakness
 Calcium deposits in heart or lungs
 Increased serum calcium

Kidney stones
 Most toxic of all vitamins

Vitamin D Sources




Fortified milk
Fortified margarine
Fortified breakfast
cereals
Small amounts in
egg yolk, salmon,
tuna fish
Vitamin E
Generic name for 8 naturally
occurring fat soluble nutrients called
tocopherols
 Absorbed with aid of pancreatic
secretions and bile salts
 Stored in adipose tissue

Vitamin E

Great antioxidant
Neutralizes free radicals
 Works with selenium to destroy
cell peroxides
 Protects lung from air pollutants
 Protects RBC
 Research on Vitamin E role in
decreasing heart disease

Vitamin E
Decreased # of sickle cells
 Helps in cystic fibrosis
 Benefit in boosting immune function
and fighting Alzheimer’s

Vitamin E Deficiencies
RBC break open
 Erythrocyte hemolysis in
premature infants (hemolytic
anemia)
 Affects vision
 Neurology problems

Vitamin E Toxicity

Interferes with blood clotting action
of Vitamin K


leads to hemorrhage with anticoagulant
drugs
MYTHS:
improves athletic skill
 enhances sexual performance
 prevents wrinkling or gray hair

Vitamin E Sources





Vegetable oils
Milk
Eggs
Fish
Cereal grains
Vitamin K



Phylloquinone
Essential for
synthesis of 5
proteins involved
in blood clotting
Involved with
CA++ in bone
development
Vitamin K
Absorbed in small intestine
 Needs bile salts for absorption
 Stored in liver
 Small amount-10 days supply
 Can be synthesized in intestinal tract
from dietary sources

Vitamin K Deficiencies
Needed daily
 Extended use of antibiotics
 Malabsorption -defects in fat
absorption
 In sterile digestive tract in newborns


Hemorrhage Disease of newborns
Vitamin K Toxicity
Red cell hemolysis
 Jaundice
 Brain damage

Vitamin K Sources





Green leafy
vegetables
Liver
Milk
Meats
Egg yolk
Vitamin C
Absorbed from small intestine
 ~ 3 months for deficiencies to
appear
 Antioxidant
 Collagen, connective tissue
 Removes Fe++ from ferritin,
activates folate

Vitamin C
Important in wound healing
 Antihistamine effect
 Depleted in

Infectious processes
 Smokers
 Burns
 Surgery


How much to supplement unknown
Vitamin C
Megadosing can cause hyperosmolar
diarrhea
 Rebound scurvy or rash when
large doses stopped quickly
 Fe++ overload

Vitamin C

Supplemented in patients with

skin ulcers
• along with vitamin C, vitamin A, zinc

spinal cord injuries
• increase acid in urine
Vitamin C Deficiencies
Scurvy- bleeding gums
 Pinpoint hemorrhages under skin
 Rough, brown scaly skin
 Massive bleeding into joints,body
cavities

Vitamin C Sources





Citrus fruits
Potatoes
Broccoli
Tomatoes
Green peppers
Vitamin B1
Thiamin
Combined with PO4 in jejunal
mucosa
 forms TPP

acts in process that converts
 pyruvate to acetyl CoA
energy

Vitamin B1 Deficiencies
Anorexia
 Severe constipation
 Lower HCL acid secretion
 General apathy & fatigue
 Severe: beriberi

paralysis and cardiac failure
 lower extremity edema
 muscle pain

Vitamin B1
Give thiamin to ETOH abusers
 Supplement in:





chronic illness
gestation
lactation
strange diets
Vitamin B1 Sources



Lean meats
Liver
Whole or enriched
grains
Vitamin B2 Riboflavin
Facilitates energy production
 2 enzymes operate at vital reaction
points of citric acid cycle
 De-amination of A2
 Light sensitive, destroyed ultraviolet
rays and fluorescent light

Vitamin B2 Deficiencies
Tissue inflammation/breakdown
 Delayed wound healing
 Characteristic cracks at corners of
mouth-cleilosis
 Tongue becomes red swollen glossitis
 Eyes burn, itch, tear

Vitamin B2 Deficiencies
Scaly, greasy skin-seborrheic
dermatitis in skin folds
 Supplement in GI diseases,
pregnancy, and lactation

Vitamin B2 Sources




Milk
Meat
Whole
grain/enriched
breads
Dark green leafy
vegetables
Niacin
Participates in energy metabolism
 Small amount made from
tryptophan
 Active in citric acid cycle
 Used in CVD to lower CHOL
 Acts as vasodilator-causes skin
flushing
 Can injure liver

Niacin Deficiencies
Weakness and anorexia
 Skin eruptions
 Dark scaly dermatitis
 Severe-confusion, pellagra
 4 D’s = dermatitis, diarrhea,
dementia, death

Niacin Sources




Peanuts
Beans
Peas
Enriched grains
Vitamin B6 Pyridoxine
Sensitive to light
 Part of coenzyme in protein
metabolism
 Converts tryptophan to serotonin
 Stimulated cerebral activity and
brain metabolism (gray matter)
 Hemoglobin synthesis

Vitamin B6 Deficiencies
Greasy, scaly dermatitis
 Microcytic anemia
 Abnormal EEG
 Infant seizures
 Isoniazid TX
 Supplements TB rx, pregnancy and
oral contraceptives

Vitamin B6 Toxicity
Large doses for treatment of PMS
 Lack of muscle co-ordination and
numbness

Vitamin B6 Sources






Peanuts
Fish
Poultry
Meat
Bananas
Enriched whole
grains
Folate or folacin
Part of building blocks of DNA/RNA
 Helps from heme in hemoglobin
 Increased needs in

periods of accelerated growth
 Etoh or drug abuse

Folate Deficiencies
Neural tube birth defects
 Oral contraceptive use
 Some anti-convulsant use
 GI disease including diarrhea
 Megaloblastic anemia
 Food processing can destroy vitamin

Folate Sources






Enriched cereals
Green leafy
vegetables
Liver
Milk
Eggs
Dried beans &
peas
Vitamin B12 Cobalmin
Bound in stomach by specific
glycoprotein called intrinsic factor
 Pernicious anemia
 Folate and B12 work together in cell
division
 True dietary deficiency only seen in
vegans

Vitamin B12
Post-gastrectomy anemia
 IM injections

Vitamin B12 Sources






Liver
Fresh Shrimp
Meats
Milk
Eggs
Cheese
Pantothenic Acid
Component of tissue enzyme CoA
 No deficiency or toxicity
 Supplements not usually needed
 Lots of jobs:

synthesis of lipids
 neurotransmitters
 steroid hormones
 hemoglobin

Biotin
No deficiency except long term TPN
 No toxicity
 Partner with acetyl CoA
 Synthesis fatty acids and A2
 Supplement not usually needed

Vitamin Supplements
In most cases, eat the food is the
best recommendation.
 Interactions between high doses of
vitamins not known.
 Long-term risks not known


Apoptosis
A GOOD Idea
The elderly
 Finicky eaters
 Very-low kcal diets
 Smokers and Alcoholics
 Pregnant and lactating women
 Certain
diseases/trauma/malabsorption

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